Which ions—positive ions or negative ions—tend to be larger and why?

Generally negative ions is known as anion and positive ions is known as cation. Anions will gain an electron to fill in an electron shell but cations will lose an electron to fill in an electron shell so that cation by losing the electron the ionic mass will be lower where as for anion by gaining an electron the ionic mass will be higher so that atom will be larger.Therefore negative ions tend to be larger than positive ions.